The data supplied by wheel sensors are employed in targeted applications using the measurements supplied by these sensors, notably:                wheel location, for the purpose of monitoring the pressure of the tire corresponding to each located wheel,        detection of overload and wear of tires,        automatic training of the sensors, or        monitoring the positions of the sensors themselves.        
At the present time, vehicle wheels usually incorporate multi-function sensors known as WFCs (an acronym for “Wheel Fitted Component” in the English terminology) in modules which may either be fixed to the wheel rim—in which case the modules are known as wheel units or WUs (an acronym for “Wheel Unit” in the English terminology)—or fixed directly to the inner face of the tire, in which case the modules are known as TMs (an acronym for “Tire Module” in the English terminology).
These WFC sensors periodically supply measurements made by pressure, temperature and/or acceleration sensors to a microprocessor integrated in a central processing unit, via a CAN bus or transceivers fitted with antennas. The set of means employed (sensors, central unit, and communication network using cables or transceivers) forms a system for monitoring the pressure of the tires, conventionally known as a TPMS system (an acronym for “Tire Pressure Monitoring System” in the English terminology).
The digital data supplied by the WFC sensors to the central processing unit indicate the successive levels of variation. On the basis of these values, the central processing unit calculates, after filtering and sampling, pressure and temperature signals which are transmitted to the on-board computer of the vehicle. The acceleration data are used, in particular, in the aforementioned targeted applications, for supplying the values of the essential parameter for these applications during the periodic transmission of the sensors, namely the angular location of the sensors in the wheels and/or the length of the footprint of the tires on the ground.
The basic parameter setting for some of the targeted applications may make use of data supplied by other methods to ensure the reliability of the results. Thus, data from the sensors of anti-lock braking systems, known as ABS systems, are correlated with the acceleration data for the angular location of the wheels. Impact sensors are also commonly used for the determination of tire footprint lengths.
These correlations are described, for example, in U.S. Pat. No. 6,112,587, and in patent application EP 2 090 862.
However, it appears that the data supplied by the WFC sensors may be seriously perturbed by various factors, in particular when the state of the road exhibits irregularities. In this case, the impacts caused in the wheels may unexpectedly initiate the transmission of data from the WFC sensors, and may completely or partially falsify the results. Thus the angular location of the wheels becomes random, or the length of the tire footprint is reduced.
In magnetic impact sensors added to WFC sensors, such as the sensor described in patent document EP 2 090 862 or the magnetometers proposed in patent FR 2 944 231, the magnetic field is modified when the sensor is in the angular portion of the wheel in contact with the ground, or when the rolling tire is flattened on the ground. The central unit then analyzes the variations of the magnetic field in order to calculate the footprint of the tire. Thus the presence of irregularities or variations in the road profile is not taken into consideration, and no tool is provided in this case to modulate the reliability of the measurements of the WFC sensors.
The invention therefore proposes to devise a tool for evaluating the reliability of the data supplied by multi-function WFC sensors of a vehicle for targeted applications, on the basis of the irregularities of the road. For this purpose, the invention proposes to use monitoring data obtained from the equipment of the vehicle for the purpose of adapting its handling, these data, if correctly identified, enabling the variations in the state of the road to be reflected directly or implicitly.
Direct monitoring equipment includes stereoscopic camera systems, radar systems and laser sensors, which directly supply information on the surface condition of the road.
Other equipment includes the suspension control systems of a vehicle, which implicitly supply data that can be used to characterize the monitoring of the state of the road. In these systems, sensors enable the shock absorbers to be adjusted so as to absorb the variations in the road surface. The U.S. Pat. No. 4,600,215 discloses sensors of this kind, in the form of ultrasonic sensors.
In vehicle suspension control solutions, such as those associated with hydropneumatic suspensions, a hydroelectronic unit with an integrated computer—known by the abbreviation BHI—receives data from a steering wheel angle sensor and body displacement sensors. The information on the angle and rotation speed of the steering wheel, together with the front and rear body heights, are processed by the BHI computer in order to regulate the suspension flow rate and pressure, as well as the height of the body. The present invention advantageously uses a BHI unit of this type to detect displacements of the vehicle body.